Determine the homolytic C-H bond strength in CH3OH employing the following data.

[kidvideo90]

DfH (CH3OH) = -201.6 kJ mol-1
DfH (H) = 218 kJ mol-1
DfH (HBr) = -36 kJ mol-1
DfH (Br) = 111.9 kJ mol-1
CH3OH + Br
CH2OH + HBr k(300K) = 1 x 106 M-1s-1; k(350K) = 4 x 108 M-1s-1
CH2OH + HBr
CH3OH + Br k(300K) = 1 x 107 M-1s-1; k(350K) = 7.7 x 108 M-1s-1

Any help would be appreciated, I just can't figure out how to even start this problem. Thanks in advance

 

[GCT]

Use the rate data to correlate with the temperature data and find the enthalpy of the reaction for the two equations.

Write the homolytic dissociation equation. Also clarify the subscripts.

 

[Blueshift5]

for your help!

To determine the homolytic C-H bond strength in CH3OH, we can use the data provided and apply the following equations:

1. Calculate the bond dissociation energy (BDE) of the C-H bond in CH3OH using the bond energies of H and CH3OH:
BDE (C-H) = DfH(CH3OH) - DfH(H) = -201.6 kJ mol-1 - 218 kJ mol-1 = 16.4 kJ mol-1

2. Calculate the activation energy (Ea) for the reaction CH3OH + Br
CH2OH + HBr using the rate constants (k) at two different temperatures (300K and 350K):
Ea = -RT ln(k2/k1) = -8.314 J mol-1 K-1 * ln(4 x 108 M-1s-1 / 1 x 106 M-1s-1) = 12.8 kJ mol-1

3. Calculate the energy released (ΔE) during the reaction CH2OH + HBr
CH3OH + Br using the rate constants (k) at two different temperatures (300K and 350K):
ΔE = RT ln(k2/k1) = 8.314 J mol-1 K-1 * ln(7.7 x 108 M-1s-1 / 1 x 107 M-1s-1) = 20.6 kJ mol-1

4. Use the Arrhenius equation (k = A * e^(-Ea/RT)) to calculate the pre-exponential factor (A) for the reaction CH3OH + Br
CH2OH + HBr at 300K:
A = k * e^(Ea/RT) = (1 x 106 M-1s-1) * e^(12.8 kJ mol-1 / (8.314 J mol-1 K-1 * 300K)) = 4.4 x 10^7 M-1s-1

5. Use the pre-exponential factor (A) and the BDE (C-H) to calculate the homolytic C-H bond strength in CH3OH using the Eyring equation (k = A * e